Posterior Percutaneous Endoscopic Technique Through Bilateral Translaminar Osseous Channels for Thoracic Spinal Stenosis Caused by Ossification of the Ligamentum Flavum Combined with Disk Herniation at the T10-11 Level: A Technical Note

M1 macrophage-derived oncostatin M induces osteogenic differentiation of ligamentum flavum cells through the JAK2/STAT3 pathway

Background

M1 macrophages (Mφs) are involved in osteogenic differentiation of ligamentum flavum (LF) cells and play an important role in heterotopic ossification. However, the mechanism by which M1 Mφs influence osteogenic differentiation of LF cells has not been studied.

Methods

The effect of conditioned medium including secretions of M1 Mφs (CM-M1) on LF cells was analyzed by GeneChip profiling and ingenuity pathway analysis (IPA). THP-1 cells were polarized into M1 Mφs and CM-M1 was used to induce LF cells. In addition, LF cells were induced by CM-M1 in the presence of cyclooxygenase 2 (COX-2) inhibitors or oncostatin M (OSM)-neutralizing antibodies. Based on the presence of OSM, knockout of OSMR or GP130 receptors, or addition of the Janus kinase 2 (JAK2) inhibitor AZD1480 or signal transducer and activator of transcription 3 (STAT3) inhibitor Stattic were examined for effects on osteogenic differentiation of LF cells. OSM secretion was quantified by ELISA, while qPCR and western blot were used to evaluate expression of osteogenic genes and receptor and signaling pathway-related proteins, respectively.

Results

GeneChip and IPA results indicate that the OSM signaling pathway and its downstream signaling molecules JAK2 and STAT3 are significantly activated. ELISA results indicate that OSM is highly expressed in cells treated with CM-M1 and lowly expressed in cells treated with CM-M1 and a COX-2 inhibitor. Besides, CM-M1 induces osteogenic differentiation of LF cells, which is weakened when COX-2 inhibitors or OSM-neutralizing antibody are added to it. Recombinant OSM could induce osteogenic differentiation of LF cells and upregulate expression of OSMR, GP130, phosphorylated (P)-JAK2, and P-STAT3. Upon knockdown of OSMR or GP130, or the addition of AZD1480 or Stattic, P-JAK2 and P-STAT3 expression were decreased and osteogenic differentiation was reduced.

Conclusion

M1 Mφ-derived OSM induces osteogenic differentiation of LF cells and the JAK2/STAT3 signaling pathway plays an important role.

Surgical Technique of Central and Over-the-Top Full-Endoscopic Decompression of the Cervical Spine: A Technical Note

Endoscopic surgery of the cervical spine is constantly evolving and the spectrum of its indications has expanded in recent decades. Full-endoscopic techniques have standardized the procedures for posterior and anterior access. The full-endoscopic approach was developed to treat degenerative diseases with the least possible invasion and without causing instability of the cervical spine. The posterior full-endoscopic approach is indicated for the treatment of diseases of the lateral part of the vertebral segment, such as herniations and stenoses of the lateral recess and vertebral foramen. There has been little discussion of this approach to the treatment of central stenosis of the cervical spine. This technical note describes a step-by-step surgical technique for central and over-the-top full-endoscopic decompression in the cervical spine, using a 3.7 mm working channel endoscope. This technique has already been shown to be effective in a recent case series with a 4.7 mm working channel endoscope, and may represent a new treatment option for central or bilateral lateral recess stenosis. There is also the possibility of a bilateral full-endoscopic approach, but this may be associated with greater muscle damage and a longer operative time. Case series and comparative studies should be encouraged to confirm the safety and utility of this technique.

Biportal Endoscopic Posterior Thoracic Laminectomy for Thoracic Spondylotic Myelopathy Caused by Ossification of the Ligamentum Flavum: Technical Developments and Outcomes

Objective: Advanced biportal endoscopic surgery techniques can be used to treat thoracic myelopathy secondary to ossification of the ligamentum flavum (OLF). This case series elaborates on a feasible biportal endoscopic technique for thoracic OLF removal and evaluates clinical and radiological outcomes.Methods: A biportal endoscopic posterior thoracic laminectomy was performed to remove the thoracic OLF. Surgical techniques have evolved from inside-out piecemeal removal methods to outside-in <i>en bloc</i> removal methods. Preoperative computed tomography was performed to analyze dural ossification and OLF types. Intraoperative videos were reviewed to observe dural ossification and to determine the surgical method. Neurological outcomes were assessed using the Japanese Orthopaedic Association (JOA) score.Results: Clinical symptoms and neurological function improved markedly after surgery (JOA score, preoperative: 12.6 ± 1.0, final follow-up: 15.6 ± 1.2). The mean operation time per segment was not short (106.6 ± 38 minutes). At early experience stages, inside-out piecemeal decompression was used and it caused intraoperative spinal cord injury. However, outside-in <i>en bloc</i> decompression technique did not induce neural complications. Postoperative segmental instability and correlated mechanical back pain were not observed.Conclusion: The biportal endoscopic posterior thoracic approach is an attractive surgical option to treat thoracic spondylotic myelopathy secondary to OLF. Piecemeal inside-out decompression can induce irreversible spinal cord injury, especially in the early experience stages. Outside-in decompression is more efficient and safer than inside-out pattern procedures by minimizing dural manipulation. Nonetheless, this technique is technically demanding and should only be performed in selected patients after acquiring abundant experience with endoscopic spine surgeries.

Comparative Clinical and Radiographic Cohort Study: Uniportal Thoracic Endoscopic Laminotomy With Bilateral Decompression by Using the 1-Block Resection Technique and Thoracic Open Laminotomy With Bilateral Decompression for Thoracic Ossified Ligamentum Flavum

BACKGROUND

Symptomatic thoracic myelopathy secondary to thoracic ossified ligamentum flavum (OLF) often requires decompression spinal surgery.

OBJECTIVE

To compare clinical and radiological outcomes in uniportal endoscopic vs open thoracic decompression for thoracic OLF.

METHODS

Retrospective evaluation of patients who underwent uniportal thoracic endoscopic unilateral laminotomy with bilateral decompression (TE-ULBD) by using the one-block resection technique compared with thoracic open laminotomy (TOL) with bilateral decompression. Radiological outcomes in MRI scan and clinical charts were evaluated.

RESULTS

Thirty-five levels of TE-ULBD were compared with 24 levels of TOL. The overall complication rate of TOL was 15% while TE-ULBD was 6.5%. Both TOL and TE-ULBD cohort had significantly improved their visual analog scale (VAS), Oswestry Disability Index, and Japanese Orthopaedic Association (JOA) myelopathy score after operation. Comparative analysis of TE-ULBD performed statistically and significantly better than TOL in improvement of final VAS and JOA scores. The mean difference ± standard deviation of VAS and JOA improvement in final follow-up when compared with preoperative state of TE-ULBD and TOL was 0.717 ± 0.131 and 1.03 ± 0.2, respectively, P < .05. The mean Hirabayashi recovery rates were 94.5% (TE-ULBD) and 56.8% (TOL). There was no statistical difference in change in preoperative and final Oswestry Disability Index and MRI volume at upper endplate, middisk, and lower endplate canal cross-sectional area.

CONCLUSION

Uniportal TE-ULBD achieved significantly improved pain and neurological recovery with sufficient spinal canal decompression, as compared with thoracic open laminectomy for patients with myelopathy secondary to OLF in our cohort.

Percutaneous Endoscopic Posterior Decompression for Therapy of Spinal Cord Compression Due to Ossification of the Ligamentum Flavum: A Long-Term Follow-up

BACKGROUND

Thoracic ossification of the ligamentum flavum (OLF) is a pathologic condition that affects ligamentation of the OLF and causes slowly progressive myeloradiculopathy. There is a trend toward performing minimally invasive surgery. In this study, we assess the long-term efficacy of percutaneous endoscopic surgical management of thoracic OLF.

METHODS

Twenty patients with thoracic myelopathy due to thoracic OLF underwent percutaneous endoscopic surgical management. We investigated clinical outcomes and neurologic improvements. Magnetic resonance imaging was performed on all patients preoperatively and postoperatively, and intramedullary signal changes were evaluated.

RESULTS

The operation time averaged at 170.4 minutes (range 110-320 minutes). The mean intraoperative blood loss was 29.6 mL (range 5-100 mL). Cerebrospinal fluid leakage occurred in 1 patient and healed well. The follow-up period ranged from 60 to 72 months. The mean score on the Japanese Orthopedic Association scale improved from (6.0 ± 1.41) preoperatively to (7.83 ± 1.40) at 1 month postoperatively to (9.67 ± 1.30) at the final follow-up (P < 0.05). At the final follow-up stage, 11 patients had excellent outcomes, 6 good, 2 fair, and 1 unchanged, according to the Hirabayashi recovery rate. No patient had postoperative deterioration in neurologic status.

CONCLUSIONS

Percutaneous endoscopic surgical management of thoracic OLF has proven to be both safe and effective for the resection of the OLF in the thoracic spine.

Thoracic full-endoscopic unilateral laminotomy with bilateral decompression for treating ossification of the ligamentum flavum with myelopathy

Background

The aim of the present study was to evaluate the curative effect and safety of thoracic full-endoscopic unilateral laminotomy with bilateral decompression (TE-ULBD) for treating ossification of the ligamentum flavum (OLF) with myelopathy.

Methods

Between January 2015 and December 2018, 23 consecutive patients with symptomatic thoracic OLF were treated with TE-ULBD. Of these, 21 (13 women and 8 men, aged 49-75 years) were included in the study and followed up for a minimum of 1 year. The mean blood loss was 15.48 mL (10-30 mL), operative duration was 78.86 min (55-115 min), and hospitalization was 5.05 days (3-15 days). The Japanese Orthopaedic Association (JOA) was used to evaluate spinal cord function, and the curative effect was defined by the JOA improvement rate. The area of OLF (AOLF), the maximum spinal cord compression (MSCC), and the area of spinal cord (ASC) were used to evaluate OLF clearance and spinal cord decompression status.

Results

At the final follow up,the JOA score was 8.33 points (5-11 points), which was a significant improvement from the preoperative 5.33 points (3-9 points, P<0.01). The excellent and good rate was 76.19% (16/21). The average preoperative AOLF and AOLF ratio were 85.27±23.66 mm² and 57.86%±11.86%, respectively, and the postoperative AOLF and AOLF ratio were 16.27±11.75 mm² and 8.13%±5.38%, respectively. The MSCC increased from 27.99%±13.51% preoperatively to 48.02%±6.66% postoperatively. The ASC was 42.90±10.60 mm² preoperatively and 64.54±21.36 mm² postoperatively. There were statistically significant differences in all parameters preoperatively and postoperatively (P<0.01). One case had postoperative hematoma, and the symptoms gradually eased after 3 weeks of conservative treatment. There were no other complications. No recurrence of OLF was detected during the follow-up period.

Conclusions

TE-ULBD is safe and effective for thoracic OLF with the advantages of reduced trauma and bleeding, and faster recovery.

Combined, Rib-Sparing, Bilateral Approach to the Ventral Mid and Low Thoracic Spine: Study on Comparative Anatomy and Surgical Feasibility

BACKGROUND

Pathologies of the ventral thoracic spine represent a challenge, igniting arguments about which should be the ideal surgical approach to access this area. Anterior transthoracic thoracotomy and a number of posterolateral routes have been developed. Among the latter, costotransversectomy has demonstrated to provide good ventral exposure with a lower, but not negligible, morbidity. The optimal approach should be the one minimizing surgical morbidity on both neural and extraneural structures while optimizing exposure.

METHODS

The authors described the combined, rib-sparing, bilateral approach (CRBA) to the ventral mid/low-thoracic spine. The technique combines a transfacet pedicle partially sparing approach on one side and a transpedicular with transverse process resection on the contralateral one. A laboratory investigation was conducted. The technique was applied in a surgical setting, and a case was reported.

RESULTS

CRBA is rib-sparing, completely extracavitary, and does not require pleural exposure and paraspinal muscle splitting, thus minimizing potential morbidity. The combination of 2 corridors ensures the greatest exposure compared with standard posterolateral approaches. The only blind corner is limited to a small area just in front of the dural sac. A bimanual approach optimizes control during surgical manipulation, even if the area of maneuverability and cross-section areas of surgical corridors are slightly limited compared to traditional costotransversectomy due to the minimally invasive nature of the procedure.

CONCLUSIONS

CRBA represents a safe and effective option to access the ventral mid/low thoracic spine. It provides great exposure and bimanual manipulation of the surgical target, minimizes potential morbidity, and avoids entrance into the thoracic cavity and paraspinal muscle splitting.

Full-endoscopic decompression for thoracic myelopathy caused by ossification of the ligamentum flavum: patient series

BACKGROUND

This study aimed to describe the least invasive surgical technique of endoscopic decompression for thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) and to review the literature available on the diagnosis and treatment of OLF.

OBSERVATIONS

The mean age of the patients was 51.2 (range, 40–62) years, and the mean preoperative, 2-week postoperative, and last follow-up modified Japanese Orthopaedic Association scores were 6.6 (range, 4–10), 9.6 (range, 7–11), and 13 (range, 10–14), respectively. All patients were discharged within 48 hours after the surgery. The mean follow-up period was 13.2 (range, 7–18) months. No complication was found perioperatively, and none of the patients had postoperative instability during the follow-up period.

LESSONS

Based on this clinical case series and literature review, the authors conclude that endoscopic decompression surgery is feasible and effective for managing thoracic myelopathy caused by OLF while minimizing surrounding tissue damage. Additionally, it enables shorter periods of hospital stay.

Full endoscopic surgery for thoracic pathology: an assessment of supportive evidence

In the last five years, surgeons have applied endoscopic transforaminal surgical techniques mastered in the lumbar spine to the treatment of thoracic pathology.

The aim of this systematic review was to collate the available literature to determine the place and efficacy of full endoscopic approaches used in the treatment of thoracic disc prolapse and stenosis.

An electronic literature search of PubMed, Embase, the Cochrane database and Google Scholar was performed as suggested by the Preferred Reporting Items for Systematic Review and Meta-analysis statements. Included were any full-text articles referring to full endoscopic thoracic surgical procedures in any language.

We identified 17 patient series, one cohort study and 13 case reports with single or of up to three patients.

Although the majority included disc pathology, 11 papers related cord compression in a proportion of cases to ossification of the ligamentum flavum or posterior longitudinal ligament. Two studies described the treatment of discitis and one reported the use of endoscopy for tumour resection.

Where reported, excellent or good outcomes were achieved for full endoscopic procedures in a mean of 81% of patients (range 46–100%) with a complication rate of 8% (range 0–15%), comparing favourably with rates reported after open discectomy (anterior, posterolateral and thoracoscopic) or by endoscopic tubular assisted approaches. Twenty-one of the 31 author groups reported use of local anaesthesia plus sedation rather than general anaesthesia, providing ‘self-neuromonitoring’ by allowing patients to respond to cord and/or nerve stimuli.

Cite this article: EFORT Open Rev 2021;6:50-60. DOI: 10.1302/2058-5241.6.200080

Current and Future of Endoscopic Spine Surgery: What are the Common Procedures we Have Now and What Lies Ahead?

The aging population around the world leads to increasing incidence of degenerative spinal conditions. There is a need for a minimally invasive technique in treatment for spinal conditions to meet the medical complexity and comorbidities that comes with aging. Principles of endoscopy are similar to minimally invasive surgery, which is to decrease pressure on soft tissue crushing from prolonged retraction, avoid soft tissue stripping and dissection, and bone and ligamentous preservation for optimal decompression without excessive destruction. Endoscopic spine surgery techniques started slowly in development in the 1970s to 2000s, with a rapid phase of development since the turn of the 21st century with endoscopic solutions developing in cervical, thoracic, and lumbar conditions with increasing complexity in nature of operation. Technological enhancement with progressively supportive literature is pushing boundaries of endoscopy from the early days of soft tissue procedure to current fusion procedures, endoscopic spine surgery techniques is covering more areas of spine than ever previously possible with good clinical results. We present a review on the current techniques available and postulated near future development for endoscopic spine surgery.

Full-Endoscopic Spine Surgery for the Treatment of Lumbar Ossification of the Ligamentum Flavum: Technical Report

BACKGROUND

Ossification of the ligamentum flavum (OLF) is a relatively common disease in East Asia. Although surgical decompression using a posterior approach is commonly used to treat OLF, there are several different treatment strategies. The purpose of this study is to clarify the technically important points for the treatment of OLF using full-endoscopic spine surgery (FESS).

METHODS

FESS was performed on 7 patients with lumbar OLF. Patients had a mean age of 62.3 years and single-level involvement. Computed tomography and magnetic resonance imaging were used to classify the OLF. Two different types of spinal endoscope were used for posterior decompression. Interlaminal and translaminal approaches were performed in 6 and 1 patient, respectively. Preoperative and postoperative pain was evaluated using the numeric rating scale score.

RESULTS

The mean operation time was 84.1 minutes. Unilateral round-type OLF was treated using a 4.1-mm working channel endoscope. The bilateral type was treated using a 6.4-mm working channel endoscope. A dural tear occurred in 1 patient with beak-type OLF, but no symptoms resulting from the tear were observed. The mean preoperative and postoperative numeric rating scale scores were 7.7 and 1.6, respectively.

CONCLUSIONS

Posterior decompression using FESS can be used to treat patients with lumbar OLF. Unilateral round-type OLF with ipsilateral radiculopathy can be treated using a 4.1-mm working channel endoscope. Bilateral-type OLF with cauda equina symptoms should be treated using a 6.4-mm working channel endoscope.